The present invention relates to the field of photography and, more specifically, to a simply-constructed, two-bladed shutter mechanism and photographic apparatus, such as a microfiche camera, which includes such a shutter mechamism.
Commonly-assigned copending application U.S. Ser. No. 071,939 filed on Sept. 4, 1979 by V. L. Cocco, P. R. Noris and R. R. Wareham discloses and claims a microfiche system comprising a microfiche camera, a microfiche projector, and a console having a mount thereon for interchangeably receiving either the camera or the projector.
With the camera mounted on the console, the system is operative in a recording mode for exposing a plurality of image areas on a card-like film unit, preferably of the self-developing type, with images of successive documents supported on a mounting glass on the console. Following the exposure of the last image area, the film unit is processed by advancing it between a pair of camera mounted pressure applying rollers. Thereafter, the system may be converted to a viewing mode by removing the camera from the mount and replacing it with the projector and also covering the document mounting glass with a translucent rear projection screen. The processed film unit is located in the projector which is operative to project an enlarged image of any microimage area thereon onto the screen for viewing. The microfiche system is charcterized by its simplicity of construction and low cost thereby making it affordable to small businesses or other organizations which may not be able to justify the capital outlay for more expensive conventional microfiche systems or services.
The microfiche camera is designed to expose a plurality of image areas arranged in orthogonal lateral rows and longitudinal columns. Typically, there may be 49 such image areas provided on a generally square image area of the film unit measuring 3.25 inches by 3.25 inches.
To record a row of images on the film unit, the camera is provided with a lens mounted for movement over a lateral row of framing gate apertures that define the image areas on the film unit and means for advancing the lens in increments to successive imaging positions to locate the lens in imaging relation with each of the image areas in the row. After exposure of the last image area in the row, a film advancing mechanism advances the film unit longitudinally one row position relative to the framing gate apertures to locate the next row of image areas in position for exposure.
Commonly assigned copending application U.S. Ser. No. 071,940 filed on Sept. 4, 1979 by P. R. Norris discloses such a camera and claims certain features thereof including a two-bladed shutter for selectively blocking and unblocking an optical path passing through the lens along which image forming light is transmitted to expose an image area.
The shutter includes an opening blade movable from a blocking cocked position to an unblocking rest position for initiating an exposure, a closing blade movable from an unblocking cocked position to a blocking rest position for terminating the exposure, and means for biasing both of the blades toward their respective rest positions. In a preferred embodiment, means for illuminating the document on the console mounting glass is provided by a camera mounted strobe flash unit which is fired by tabs on the shutter blades when the shutter is in its open condition. Also, the operation of the shutter must be coordinated with the movement of the lens which is driven by a rotatable barrel cam to its sequential imaging positions.
In the illustrated embodiment, the lens advancement and shutter operation is effected by a mechanical actuating system whereby during movement of a cycle button in one direction, the barrel cam is rotated to move the lens to its next postion and the shutter blades, located at the rest position in a closed condition, are moved simultaneously to their respective cocked positions. A latching system is provided for releasably latching the closing blade in the cocked position. In response to releasing the cycle button, it moves in the opposite direction allowing the opening blade to move from the cocked position to the rest position thereby opening the shutter. The strobe unit is fired when the shutter is in its open condition and a projection on the opening blade actuates the latch when the opening blade reaches the rest position to thereby release the closing blade for movement to its rest position to terminate the exposure.
While the shutter works as intended, the provision of the mechanical closing blade latch, the latch release on the opening blade, and structure on both of the blades for coupling them together for simultaneous movement to the cocked position, make the blade and actuating structures more complex and therefore more expensive than is desirable.
Two bladed shutters are, of course, well known in the photographic prior art. Generally, however, these shutters are more mechanically complex and/or costly than is desirable for incorporation into a low cost microfiche camera.
For example U.S. Pat. No. 3,326,105 discloses a two bladed shutter in which the blades are coupled together by an over center toggle spring arrangement for sequential movement. Other shutters rely on separate latches for the opening and closing blades and provide complex arrangements for sequentially unlatchig the blades. Representative examples of such shutter mechanisms are found in U.S. Pat. Nos. 2,457,679; 3,082,673; 3,430,547; and 3,491,672. Another class of two bladed shutters employs an expensive electromagnet for releasably holding the closing blade in the cocked position as shown in representative U.S. Pat. Nos. 3,461,784; 3,461,785; 3,468,228; 3,533,346; 3,545,352; 3,557,678 and 3,952,317.
Some of the mechanical complexity of the above-noted shutters is attributable to a requirement that the shutter speed be variable. In the present application a variable exposure interval is not necessary because the exposure is controlled by a known quantity of light provided during a brief exposure interval by the electronic strobe unit while the shutter is open. Also, many of these shutters are not particularly well suited for incorporation into a microfiche camera where the opeation of the shutter must be coordinated with the movement of the lens between successive imaging positions.
Therefore, it is an object of the present invention to provide a simply constructed and low cost two bladed shutter mechanism.
It is another object to provide such a shutter mechanism that is suitable for use in a low cost microfiche camera and is an improvement over the shutter disclosed and claimed in the previously-noted application U.S. Ser. No. 071,940.
Another object is to provide a photographic apparatus, such as a microfiche camera, having a simple mechanically actuated two bladed shutter that is automatically actuated during the course of cycle of camera operation in coordination with the incremental movement of the camera's objective lens.
Yet another object is to provide such a camera wherein means for controlling the movement of the opening and closing blades are directly coupled to and are operated by structure for incrementally advancing the lens along a path of travel to successive imaging positions.
Other objects will, in part, be obvious and will, in part, appear hereinafter.